Posted by
Joachim Wesner on
May 08, 2007; 12:45pm
URL: http://imagej.273.s1.nabble.com/FT-math-motion-blur-removal-tp3699574p3699577.html
HI
The noise-free case works so nicely especially because the assumed "1d
spread function" has a sudden onset and
end, i.e. sharp edges, which mean it´s FT has still some sizeable spatial
frequency content up to half the pixel spacing.
For real world blurring with fuzzy, smooth onset and ending of the
blurring kernel, noise senitivity will be
even worse than the noisy, otherwise perfect case discussed here
Joachim
ImageJ Interest Group <
[hidden email]> schrieb am 08.05.2007 10:47:22:
> High Gabriel,
>
> maybe it is the "divide by zero" problem mentioned by Filip
> Rooms that causes your problems?
> If I run the MotionBlurRemoval macro as it is, it works perfectly.
>
> If I add "Specified Noise" with a standard deviation of 2800
> on the "Motion Blurred" image, the result looks awful.
> 2800 is roughly the sum of the PSF pixels, and thus it is the
> factor that "Motion Blurred" is multiplied by with respect to
> the input image. So this amount of noise only corresponds to
> one grayscale step of the input image, and it completely kills
> the result.
>
> Thus, for a "real world" pictures, where noise and
> nonlinearities are present and where the point spread function
> (PSF) is not exactly known, one has to use more elaborate
> methods (Wiener Filter, Maximum Entropy...)
>
> Michael
> ________________________________________________________________
>
> On 8 May 2007, at 10:11, Gabriel Landini wrote:
>
> > On Tuesday 08 May 2007 05:59:45 roger bourne wrote:
> >> How do I divide an FT by another FT (or the image of its power
> >> spectrum)?
> >>
> >> I am trying to demonstrate removal of motion blur by division of the
> >> blurred image FT by the FT of the blur vector.
> >
> > There is this macro that shows blurring/deblurring:
> >
> >
http://rsbweb.nih.gov/ij/macros/MotionBlurRemoval.txt> >
> > I have tried to deblur other images by specfying the blur vector as
> > in the
> > program above, but I cannot make it work. (I must be missing
> > something quite
> > obvious).
> >
> > Please post here if you find a way of doing motion deblurring this
> > way.
> >
> > Cheers,
> >
> > Gabriel
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